The Life of Marietta Blau - Austrian Physicist and Pioneer of Particle Physics

{enclose vol14_blau.mp3}Marietta Blau was an Austrian physicist who made her most important discovery for nuclear physics, the "stars of disintegration," a few months before the annexation of Austria by the Germans. With the help of Albert Einstein, she found asylum in Mexico, a country where technical and scientific education was just beginning and which was far from the centers of nuclear research. Marietta Blau could not carry on with her scientific work in Mexico but the photographic method for nuclear physics, which she had pioneered, proved to be an invaluable tool for discovering new fundamental particles in the next decades and led to the award of the Nobel Prize to British scientists.

Ariadne Press, a small publishing house in California that specializes in studies of Austrian literature, culture, and thought entered a new field in Spring 2007 by publishing the biography of this great Austrian scientist.

The book Marietta Blau, Stars of Disintegration: Biography of a Pioneer of Particle Physics by Brigitte Strohmaier and Robert Rosner depicts the life of the Austrian physicist Marietta Blau (1894-1970) and discusses her contributions to nuclear physics. The biographical part of the book discusses her family and social background, her friendships, her personal characteristics, and the political events that shaped her life.

{access view=guest}Access to the full article is free, but requires you to register. Registration is simple and quick - all we need is your name and a valid e-mail address. We appreciate your interest in bridges.{/access} {access view=!guest} Blau's childhood in Vienna during the Fin de Siècle

Marietta Blau came from a middle-class Jewish family, and was brought up in an area where many Jews were living, such as the families of Sigmund Freud, Lise Meitner, and Carl Djerassi. Her father was a lawyer. For her family, music was always very important and her uncle had founded a publishing house for music, which was later managed by her brother Otto. Marietta was educated in the first Vienna high school that prepared girls for university education. Nearly half the girls attending this school were Jewish. Blau began to study physics in 1914, at a time when all men were called up for army service. Both of Marietta's brothers served as officers during the war. She graduated in 1919, just after the disintegration of the Austro-Hungarian Empire, when life in Austria became difficult because of the impoverishment and, particularly for Jews, because of the growing anti-Semitism.

Marietta Blau was nearly forgotten in Austria as a result of her emigration to Mexico after the annexation of Austria in 1938, although she was considered an extraordinarily gifted physicist by Albert Einstein and was nominated three times for the Nobel Prize, twice by Erwin Schrödinger.

The Austrian scientific community only became aware of the importance of Marietta Blau and her achievements when a team of scientists and historians published her biography in 2003. Now, Marietta Blau's name is mentioned at all occasions when Vienna University refers to her famous alumni, and a hall in the main building of the university has been named Marietta Blau Hall.

The "Radiuminstitut" in Vienna - Blau's working place

The "Radiuminstitut," where Blau developed the photographic method, was an institution that belonged to the Austrian Academy of

Radiuminstitut

Sciences. It had been founded in 1910 with a donation of a wealthy lawyer, Karl Kupelwieser. This was quite unusual as, in contrast to the Unites States, nearly all academic and research institutions in Austria were (and still are) financed and run by the government.

The interest in radioactive research was rapidly increasing in Austria at the beginning of the 20th century, as a result of Marie Curie's discoveries - particularly as the most important uranium mine, from which radium could be obtained, was in Joachimsthal, Bohemia, still a part of the Austro-Hungarian Empire. The Academy of Sciences arranged the extraction of radium from 10 tons of tailings from uranium production and thus owned the largest amount of radium in the world. The Radiuminstitut cooperated closely with the physical institutes of Vienna University and was headed from the beginning by Stefan Meyer, a former assistant of Boltzman, who was an excellent team manager. Meyer shaped the character of the institute for many decades until he was forced to retire by the Nazis in 1938. Research carried out during the institute's first decade led to the award of two Nobel Prizes: Victor Hess, who worked in the institute for several years, received the Nobel Prize for physics for his discovery of cosmic radiation, and Friedrich Paneth, another assistant at the institute, worked on the first radioactive-tracer experiment and collaborated with Georg Hevesy who later received the Nobel Prize for chemistry. The Radiuminstitut remained an important research institution after WW I, and continued to attract scientists from abroad while other branches of academic life in Austria suffered considerably as result of the impoverishment and the political instability of the newly constituted Austrian Republic.

After graduation, Blau worked for two years in Germany, specializing in problems connected with X-rays, first in an industrial company and then at Frankfurt University. In 1923 she returned to Vienna to care for her mother and started to work at the Radiuminstitut without any salary. Having physicists to work on a volunteer basis was customary at the Radiuminstitut, as the Academy of Sciences did not have enough funds for their salaries. This may be one of the reasons why an exceptionally high percentage of the people working in the Radiuminstitut were women. Many of these women were supported by their families, just as Marietta Blau was.

Hans Pettersson

Hans Pettersson, a marine scientist from Sweden, first came to the Radiuminstitut to measure the radioactivity of deep-sea mud, but he soon became interested in studies of atomic disintegration, which had first been initiated by Rutherford in 1919. At that time particles emitted in nuclear reactions could only be detected by the scintillation method. This method relied on the phenomenon that the radioactive rays cause light flashes on special screens, which can be observed and counted. As this method was subject to errors, Petterson and his collaborator G. Kirsch looked for a more reliable method, and Petterson asked Blau to investigate whether the impact of radioactive rays on a photographic emulsion could be used for the detection of such rays. In 1925 Blau published the first paper dealing with his question, and in the following years she published numerous papers on the photographic effect and its quantification by protons and α-particles. The main objective was to distinguish between α-particle tracks and proton tracks. After Chadwick's discovery of the existence of neutrons in 1932, Blau developed with Hertha Wambacher, first her student and then her close collaborator, a method for the detection and the determination of the energy of these particles. This was achieved by adapting the photographic emulsions to the requirements of nuclear research. For this achievement, in 1937 the two women received the most prestigious science prize in Austria, the Lieben Prize.

Since 1932, Blau had been trying to detect cosmic rays with the photographic method, and in 1937 Blau and Wambacher were allowed to expose photographic plates at the cosmic ray observatory on Hafelekar, a 2300-meter mountain. On plates exposed for several months, a new pattern of tracks was discovered, namely that of several reaction products starting where cosmic ray-induced nuclear reactions had taken place. Due to the star-like shape of these tracks they were called disintegration stars. The discovery of the disintegration stars was met with great interest in scientific circles, particularly by theoretical physicists.

Blau and Wambacher published the results of their investigation in Nature, one of the most prestigious scientific journals. Although

Marietta Blau

the two women began to gain recognition both in Austria and abroad, the situation in the Radiuminstitut deteriorated due to political developments. Wambacher, who had supported right-wing political organizations since her youth, was more and more influenced by Georg Stetter, an assistant at the physics institute who was a member of the Nazi Party, which was officially illegal at that time but very active. The Norwegian chemist Ellen Gleditsch, who saw the situation during a visit to the Radiuminstitut, invited Blau to come to Oslo for the summer term in 1938. Blau accepted the invitation and left Vienna for Oslo on the day that the German invasion started, realizing that she would not be able to come back.

A month before the annexation of Austria by the Germans, Einstein had recommended to Mexican friends that they should invite Marietta Blau. He wrote: "In Vienna the exceptionally talented Dr. Marietta Blau, working in the field of radioactivity, is there the leading expert. She will, for well-known political reasons, have to leave her home country sooner or later. She is known in the scientific world for the photographic method ... If you succeed in bringing this scientist to Mexico City you would do an excellent service for the development of science there."

Stefan Meyer

At the Radiuminstitut in Vienna, all persons of Jewish descent, including Stefan Meyer, were immediately removed after the Anschluss, just as in all other academic institutions. This opened career opportunities for people like Georg Stetter or Hertha Wambacher, who had been Nazis for a long time.

In Summer 1938 Blau received an invitation to teach at the Escuela Superior de Ingeniería Mecánica y Eléctrica (ESIME), a department of the newly established Instituto Politécnico Nacional (IPN), as a result of Einstein's recommendation. She accepted the invitation to come to Mexico together with her mother, as it was extremely difficult for refugees to obtain a visa for any country in the world.

In Mexico she was disappointed to see that at the ESIME she had practically no opportunity for scientific work. As the only woman working in the ESIME, she had many problems. But now she is celebrated in Mexico as one of the great scientists who worked in the IPN when it started. As she could not work in her own field of research, she began to study problems connected with the geographic position of Mexico, such as the effect of solar radiation on a population living at high altitudes in a tropical zone. She also studied the radioactivity in minerals and springs in various parts of the country. While she was in Mexico, far from the centers of nuclear research, the photographic method that she first developed was used for new discoveries in nuclear physics.

Staff at the ESIME (Marietta Blau, first row left)

In 1944, after the death of her mother, Marietta Blau immigrated to the United States, at first to New York City where her brother was living. She was already 50 years old when she started to work in the research department of an industrial company, where she developed several devices for which radioactive isotopes were used and filed patents for some of them. Blau was not very happy with this kind of work and started to look for another position, especially when the company moved to Janesville, a small town in Wisconsin, where she felt completely isolated.

In 1945 after the liberation of Austria, many Nazis, including persons like Stetter and Wambacher, had been removed from academic positions. Berta Karlik, a friend of Marietta Blau, became the director of the Radiuminstitut as Stefan Meyer was too old to work again in this position. However, many of the former Nazis were reinstated after a few years, and Stetter was appointed as full professor of physics. He wrote an inspired obituary for Wambacher who had died of cancer in 1950, giving the impression that Wambacher was the major personality in developing the photographic method.

Blau and Wambacher had been nominated for the Nobel Prize in 1950 by Erwin Schrödinger for their discovery of the disintegration

Stars of Disintegration, from a protocol of the Austrian Academy of Sciences (1937)

stars. However the Prize was awarded to C.F. Powell, who had discovered the pion with the help of the photographic method. Powell wrote in his autobiography that he started to use this method for the investigations for which he received the Nobel Prize only after he learned from Walter Heitler, who personally knew Blau, of Blau's and Wambacher's papers.

During this period, Blau had left the industrial company and in 1948 was offered a job at Columbia University as a scientific staff member. As Blau was known to be an expert in detecting particles with photographic emulsions, it was her job at Columbia University to develop a research program using this method for the investigation of particles produced by fission reactors. After two years, she took a position at Brookhaven National Laboratory, where such particles were produced in larger high-energy machines. She remained there for six years, but as her work in this institution was very strenuous and she was more than sixty years of age, she left Brookhaven in 1956 and took up an appointment in a small private university in Miami. In Miami she continued with her research on particle physics and motivated some young physicists who worked there to join her in this research program.

In 1960 Blau decided to return to Vienna, partly because she felt homesick and partly for health reasons. In Vienna she was honored with the Schrödinger Prize of the Academy of Sciences but she was very disappointed to see that persons like Stetter were again active at the university. She guided some students with their dissertations in high energy physics but she remained at the periphery at the Radiuminstitut until her death in January 1970.

When Marietta Blau once asked one of her professors whether there was a possibility for her to become a Dozent (assistant professor), she was told, "Being Jewish and a woman, that is too much, there is little chance." This sentence sums up better than anything else the problems she had to face all her life.

The fact that Marietta Blau is now celebrated for her achievements both in Austria and in Mexico raises hopes that the world has changed for the better - and the stars of disintegration will be linked to her name, as she so fully deserves.

The author of the above article, Robert Rosner, is a chemist who previously worked at the Loba Chemie Company in Austria. He co-authored the book Marietta Blau - Stars of Disintegration: Biography of a Pioneer of Particle Physics with Brigitte Strohmaier.

Keeping in line with our mission of "Bridging Research and Innovation between Austria and North America", Bridges focuses on the dynamic elements of the Austrian and European, American and Canadian science, innovation and technology policy. Visit Bridges to stay in touch with the latest developments in transatlantic science, innovation and technology policy and how they affect our lives.